The present invention relates to construction materials and methods and more particularly to a multi-directional, interlocking, hollow modular building element, designed to increase stability of load-bearing walls or structures and minimize active pressure.
In building of load-bearing constructions involving filling materials, such as supporting walls, dams and artificial islands, the active vertical and horizontal pressure of the filling material must be taken into consideration. The width of the slope needed to absorb the active pressure exerted by the filling material is proportional to the height of the filling material.
In order to absorb active pressure and to prevent slippage, sinkage etc. of load-bearing constructions, various methods are used, such as rock terraces, or thick, heavy, retaining walls. These methods generally require the use of a large amount of building material, ground area and area of foundations.
Load-bearing retaining walls, supports and other similar structures have traditionally been constructed of concrete poured at the site, a process which is time-consuming and labor-intensive. To save time and expense, precast building blocks have been developed for use in erecting retaining walls, supports and the like, some of which are suggested for use in constructing a bridge abutment.
In U.S. pat. 4,982,544 to Smith, there is described a precast concrete module for use in constructing retaining walls capable of sustaining large vertical loads. In constructing a load-bearing wall using these modules stacked in rows, a stabilizing means is required, such as metal sheets inserted through slots in the rear connecting walls. The module described by Smith has a front wall, a partition wall, at least two front connecting walls and a rear connecting wall. The region between the front walls and the partition walls of the assembled modules is filled with poured concrete to create a load-bearing retaining wall. The step of pouring concrete is again time-consuming.
A particularly advantageous type of building block is that in which individual elements interlock, forming a secure, stable structure requiring little or no cement or other adhesive material, thus reducing the cost of material and time required for construction.
Several types of interlocking blocks have been described, including the following patents:
U.S. Pat. No. 5,181,362 to Benitez;
U.S. Pat. No. 5,588,271 to Rabassa;
U.S. Pat. No. 4,651,485 to Pitchford;
U.S. Pat. No. 5,379,565 to Vienne;
U.S. Pat. No. 4,514,949 to Crespo;
U.S. Pat. No. 4,573,301 to Schwartz,
U.S. Pat. No. 4,627,209 to Wilkinson,
U.S. Pat. No. 4,075,808 to Pearlman;
U.S. Pat. No. 4,031,678 to Shuring; and
U.S. Pat. No. 3,936987 to Calvin.
All of these describe a design in which blocks can be connected at their upper and lower surfaces and along two of their four vertical sides. This enables building of a construction having only one row of bricks in a horizontal direction, and not a continuous structure extending in all directions, thus limiting the load distribution, and ultimately the load-bearing capacity of the structure.
In addition, many of these interlocking blocks comprise a solid unit and do not have internal cavities to facilitate the placement of insulation, pipes or conduits. In such solid units, the use of filling material, which may be used to add weight to the modules, is prevented. This may be a particular disadvantage in the case of a retaining wall in which such filling could add weight to the modules to counteract the extrenal forces exerted on the rear of the wall.
An interlocking block and a retaining wall system derived from such blocks is described by Risi (U.S. Pat. No. 4,815,897). In this wall system, blocks are arranged in end to end relation and one upon the other in an overlapping manner, with projections on the upper surface of one layer fitting into recesses on the lower surface of the upper layer. This system does not have a very high level of stability and is not suited for bearing large vertical loads.
Therefore, it would be advantageous to provide an interlocking system of hollow, load-bearing building elements which can be used with or without filling material in mortarless construction of retaining walls, overhead passageways, artificial islands and the like.
Accordingly, it is an object of the present invention to overcome the disadvantages of the prior art and provide interlocking building elements which can absorb large horizontal or vertical pressures, and thus eradicate or minimize the effects of active pressure.
It is a further object of the present invention to provide interlocking building elements that can be connected along each face to form a stable, continuous, multi-directional structure, requiring no cement or other stabilizing material.
It is a further object of the present invention to provide elements which are hollow and can be filled with any required material.
In accordance with a preferred embodiment of the present invention, there is provided a system of modular interlocking building elements comprising a plurality of rigid, hollow polygonal elements having vertical faces, a first portion of said polygonal elements provided as base elements arranged as a base layer, a second portion of said polygonal elements provided as interlocking elements arranged as an intermediate layer above said base layer, a third portion of said polygonal elements provided as interlocking elements arranged as an upper layer above said intermediate layer, said interlocking elements in said intermediate layer being formed with a vertical slit in all of said vertical faces, said interlocking elements in said upper layer being formed with vertical slits in at least two of said vertical faces, such that said at least two vertical slits of each of said intermediate layer elements engage said base elements, and said at least two vertical slits of each of said upper layer elements engage said intermediate layer elements, said base, upper and intermediate layers providing a mortarless, multidirectional load-bearing construction.
According to a preferred embodiment, there is provided a series of interlocking, quadrilateral, hollow elements, each provided with vertical slits for engaging the upper half of the face of one or two similar modular elements. The interlocking elements form a continuous structure, which will counteract the active pressure exerted by any filling material. Thus, the load exerted on the structure develops forces which are constrained within the element and these forces are not spread horizontally to the surrounding foundation.
A feature of the present invention is to provide modular elements for use in construction of structures in which active pressure is a factor, such as retaining walls, bridge abutments, ramps, dams, artificial islands, etc.
An advantage of the present invention is the minimization of active pressure, resulting in economization on filling material, ground area, area of foundations, etc.
A further advantage of the present invention is that the interlocking structure of the elements enables construction in all directions, permitting even load distribution and adding to the load-bearing capacity of the entire construction. The vertical and horizontal interlocking enables the construction of an even surface without the use of adhesive material between the elements.
The modular elements of the present invention may also be used as building construction elements without filling material, for example in the construction of overhead passageways.
Additional features and advantages of the invention will become apparent from the following drawings and description.